(1) Field of the Invention
The present invention relates to an erasable electrically programmable memory cell of a type useful in VLSI technology, more specifically to an EPROM cell capable of providing a means to increase the density of cell array devices.
(2) Description of the Invention
More efficient utilization of device area in VLSI technology is a prominent objective in order to increase the density and number of devices and memory cells on a semiconductor chip in order to reduce cost and increase the speed of operation. A known technique is to place various elements, i.e. transistors, capacitors, etc. in trenches to achieve greater element density. Examples of such utilization of trench structures in EPROM devices are shown in U.S. Pat. No. 4,975,383 and 4,975,384.
Accordingly, an object of this invention is to describe an improved method and resulting device structure for making highly dense EPROM products.